Scanner Repeater Switch

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Gilligan

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Does anyone know where I could get a switch that would plug into both the headphone jack of a scanner and the microphone jack of a two-way that would be voice activated and key up the transmitter when there's audio on the scanner? The same could be used as a simple repeater setup for ham radio or whatever as well, considering you have two handhelds side by side. I see that Ramsey Electronics has a VOX switch kit, but I don't want to go to that much trouble. Is there already something out there that does this?
 

n2mdk

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The first thing you should try is putting on some headphones and listening to the scanner when you transmit. There's a good chance that if the 2 are close to one another the scanner might get desensed by the transmitter. So the idea might not work, if you can figure out a way to do it.
 

n5usr

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Unless you are very far away in frequency (as in - maybe - high UHF receive, low-band transmit) and have the two antennas separated as well, you are going to have desense. Scanners are generally particularly bad about it.

If you connect both devices to the same antenna, and use a diplexer, then you can certainly get away with "crossband" repeating - one receives on (say) VHF, the other transmits on UHF. Many amateur radio dual-band mobile rigs have this feature built in. The diplexer keeps the (bulk of the) RF energy from the transmitter from affecting the receiver.

If you want to retransmit on the same band as the received signal, then you need either a proper duplexer (note the "u" not "i" - they are much more expensive, although some manufacturers use the "duplexer" name improperly for band-separating diplexers) or you need to separate the antennas several wavelengths apart vertically (for typical FM transmissions).

Also, be careful about what you retransmit. You don't want to just rebroadcast all scanner traffic, the powers-that-be won't like that too much...
 
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